3G cell phone help

When I purchased my iPhone I signed up prepaid so I did not keep my old AT&T cell number. I still have the 2nd phone so I want to take the SIM out of my old RAZR and pop it into a 3G cell phone so I can tether it to my MacBook Pro for internet access.

Can any one recommend a 3G phone that will tether through bluetooth and is OS X compatible?

OK, I went out and I bought a Motorola v3xx and it shows 3G. How do I go about tethering it to my Mac? I connected it to my Mac via USB and it does not show up in the network system prefs. I connected via bluetooth and it shows up.

Can anyone help me with the network settings to set this up so I connect via 3G?

Well, I got the phone and I got it setup. I can't connec via 3G faster than 300-400kps so I guess the phone is going back.